Rice bran peptide with -glucosidase inhibition activity: Preparation, evaluation and molecular mechanism

The role of bioactive peptides in diabetes management has attracted extensive attention. In this study, the 1-3 kDa fraction of rice bran peptides (RBPs) was obtained by the hydrolysis of alkaline and dispase, and the following ultrafiltration demonstrated excellent alpha-glucosidase inhibition activity with an IC50 value of 1.17 +/- 0.08 mg/mL and exhibited postprandial hypoglycemic activity in vivo. Enzymatic kinetics studies revealed that RBPs (1-3 kDa) inhibited alpha-glucosidase via competitive inhibition. Thirty-two peptides were characterized from RBPs (1-3 kDa) by LC-MS/MS. Virtual screening was applied to screening the new potential alpha-glucosidase inhibitor, and NVEKKDPTGA (NA -10) with a binding energy of -10.24 kcal/mol to alpha-glucosidase was selected as the most promising peptide. Molecular docking reflected that Ala at the C -terminal and KK amino acid cluster play a key role in forming hydrogen bonds with the catalytic site of alpha-glucosidase, which might be critical for the alpha-glucosidase inhibitory effect. This study proved that RBPs could be a promising bio-factor food ingredient for diabetes prevention.